Referring to FIG. 1, a conventional dual purpose bicycle 1 suitable for a child includes a frame member 11, a front wheel 12, two crank arms 13, two pedals 14, a wheel axle 15, and two fastening members 16. The front wheel 12 is mounted to a fork portion of the frame member 11. The wheel axle 15 extends through the fork portion of the frame member 11 and the front wheel 12. Each of the crank arms 13 has a cylindrical coupling portion 131 removably and rotatably engaging a respective one of opposite ends of the wheel axle 15 via a respective one of the fastening members 16, and a distal portion opposite to the coupling portion 131 and connected to a respective one of the pedals 14.
During use, the crank arms 13 can be engaged with the wheel axle 15, and rotation of the front wheel 12 and the crank arms 13 are driven by a child pedaling the pedals 14, so as to allow the movement of the conventional bicycle 1. The child can learn how to ride the bicycle 1 to move back and forth while maintaining his/her balance. On the other hand, the crank arms 13 can be detached from the wheel axle 15, and a child or a toddler can put both feet on the ground and learn how to walk using the conventional bicycle 1 as a baby walker.
However, the fastening members 16 of the conventional bicycle 1 are relatively small in size, and an additional tool (e.g., a screwdriver or a wrench) is required to secure and remove the fastening members 16 to and from the bicycle 1, thereby rendering inconvenience for an operator. Furthermore, such small fastening members 16 may be easily lost during securing and removal processes. In addition, due to the circular configuration of the coupling portions 131, respective engagement between the coupling portions 131 of the crank arms 13 and the opposite ends of the wheel axle 15 is relatively unsecured.